: Although many factors contribute to the excess asthma morbidity and mortality in US inner cities, strong epidemiologic evidence now points to cockroach allergen exposure as an important risk factor. During the first 3 years we began a randomized controlled intervention trial of cockroach allergen abatement in inner-city homes. Recruitment has been difficult, but with extensive changes in personnel and creative new recruitment strategies, we have increased our recruitment rate to enable the original goals of the trial to be completed. In addition, we have tested the feasibility of reducing cockroach allergen in participant's homes by 90 percent and have demonstrated that our proposed intervention is feasible. Therefore, we request an additional 3 years to complete the trial as originally approved. In the next 3 years, we will recruit children aged 6-18 years with moderately severe asthma, a positive skin test to cockroach, live in a home that is infested with cockroaches and have elevated Bla g 1. Each child and their parent will undergo a baseline evaluation that will include questionnaires. The child will undergo allergy skin tests, serum for IgE antibody to cockroach, spirometry and methacholine inhalation challenge. We will visit their home to inspect, collect settled dust for cockroach allergen (Bla g 1) analysis and assess cockroach numbers with passive traps. After completing the baseline period, we will randomize 71 children to complete the planned sample of 50 families to roach intervention, and 50 to control intervention for a 6-month single blind trial. Roach intervention will consist of extermination from a professional pest control company combined with mattress covers and cleaning by professional home cleaners. Control intervention will consists of education and mattress covers but they will receive the full intervention at 6 months. Home visits will be repeated at month 2, 4 and 6 to inspect, collect settled dust specimens for Bla g 1 allergen analysis and to monitor live roach population with passive traps. Families will return to a study clinic at month 2, 4 and 6 to complete questionnaires regarding symptoms, medication use and environment, and to allow the child to perform a spirogram before and after albuterol. At 6 months the children will perform a methacholine inhalation challenge and have a repeat measure of serum IgE to cockroach allergen. The effect of environmental intervention in the 2 groups will be compared in terms of the primary clinical variable, asthma symptoms in the last 2 weeks and the primary process variable, settled dust cockroach allergen concentrations. Secondary variables, including medication use, acute care visits, school loss, FEVI and methacholine responsiveness will also be compared.